If human carbon dioxide emissions killed off these puffins, why did their numbers rapidly increase for almost forty years before their recent decline?

Big downturn in number of puffins at UK's biggest colony - Science

Breeding pairs of the unique Atlantic puffin at the site have reduced from nearly 70,000 in 2003 to 41,000 pairs this year, a dramatic decrease from the expected 100,000 had normal rates of increase been applied.

The dramatic fall comes after almost forty years of rapid population increase according to research carried out by the Centre for Ecology & Hydrology released this week.

“Something worrying appears to have happened over last winter and probably the one before," said Professor Mike Harris, Emeritus Research Fellow at the Centre for Ecology & Hydrology who led the study. "Puffins appear to be joining the ranks of other seabirds in the North Sea that are suffering reduced breeding success and decline in numbers.”